Semmelweis reflex
The reflex-like rejection of new evidence because it contradicts established beliefs or practices. It is named after Ignaz Semmelweis, a doctor in the 1800s whose finding that handwashing saved the lives of new mothers was dismissed by his colleagues.
The name is a popular metaphor, not an effect that researchers have measured under this name.
In everyday life
Many doctors at first resisted evidence that most stomach ulcers are caused by bacteria, because stress and spicy food were the accepted explanations.
A new analyst shows data proving the team's trusted sales forecast has been off for years, and senior managers wave it away at once because 'this method has always worked.'
Why your mind does this
Holding steady beliefs lets us act without rethinking everything each time. Favoring information that fits what we already know is fast, protects our sense of being right, and keeps our picture of the world stable and coherent.
Its family, in 30 seconds: Confirms beliefs
How to spot it
Notice when your first reaction to new evidence is to dismiss it because it clashes with how things have always been done.
How to counter it
When evidence challenges a standard practice, run a small, fair trial before accepting or rejecting it.
Habits that catch it
- Decide what would change your mind
Set the evidence you would need before you go looking. Moving the bar afterwards is a warning sign.
Same family: Confirms beliefs
SourcesBest & Neuhauser (2004)·Wikipedia